The present invention relates to a machining unit, in particular a machine for routing and/or boring wood preferably (though not exclusively) in the form of predominantly flat panels.
It is widely appreciated in the art field of woodworking machines (the field to which the invention specifically relates, though without excluding the possibility of its application in similar fields concerned generally with the processing of parts, whether machining by the cutting of a chip, or the fitment of fasteners, accessories, etc.) that one of the factors most liable to influence the output capacity of a work station, i.e. a unit composed of a work table, infeed and outfeed sections and at least one tool, is down time, or in the parlance of some authors, time that cannot be "hidden".
The significance of this expression derives from the fact that time not strictly of an operational nature (i.e. time needed to change the workpiece, or to effect a change of tool, or a set-up, etc.) tends in reality almost never to be "covered" by a parallel active step in which the tool engages the work; this is even more of a drawback in machines of the latest generation, using numerical control, in which the typical operating times for tools are far less than the times taken to change or position the work: accordingly, one must conclude that such machines do not effectively operate in a situation where down time can be hidden, and consequently that their technological sophistication is not in proportion to their output potential.
The main operations typically occasioning down time are: the infeed/outfeed of work from/to a conveying surface onto and from the table (almost invariably horizontal) on which the work can be clamped and positioned in relation to the tool; clearing the work table of chips or dust generated by machining; tipping solid scrap from the table; changing tools at the end of the machining run and setting up for a new size of piece, and so forth.
Working to a general model of construction for a machining unit composed, as already intimated, of a horizontal table on which to secure the work and a tool assembly mounted over or alongside the table, it has been sought hitherto by means of particular expedients to minimize the down time in question: by way of example, such expedients have centered on the adoption of palletization equipment designed to operate in conjunction with special feed systems (some employing robotics) by which the workpieces are supplied to the machining unit, as well as on ways of speeding up the tool change (using special revolver systems), etc.
Notwithstanding the undoubted reductions in down time that have been achieved through the adoption of improvements as outlined above, these have not been accompanied by a proportionate increase in output to levels commensurate with the essential operating capabilities of machines now available for purchase, whereas in the meantime, the overall cost of such machines have risen (and in no small measure). Thus it happens, in practice, that there are CNC units of ultrahigh manufacturing potential, currently in circulation, which are able to perform notably complex machining operations on a workpiece in just a few seconds but which also require an inordinately long time (almost triple the machining time) for completion of the auxiliary operations mentioned previously, albeit these are a mandatory part of the machining cycle.
This disparity between active and passive times is accentuated further in the field of machines with medium-high output capabilities, and in particular where the work being machined exhibits the maximum dimensions accommodated by the unit (such as large desks or tabletops): in this instance, down times are prolonged precisely by reason of the machine architecture, which restricts the possibility of effecting intermediate operations between one item and the next as the line is completely occupied by the item currently being machined.
An additional drawback encountered in conventional machines, likewise by reason of their architecture, is the practical problem of confining and removing the waste generated by machining, which stems from the difficulty in achieving a separation between the machining area and the infeed-outfeed station occupied by the operator, and is accompanied by a series of negative consequences connected with the effects of pollution from dust, noise, etc.
Accordingly, the applicant discloses a machining unit for wood of which the design is based on the premiss of utilizing a plurality of work tables, not, however, fixed in a horizontal position, but rotatable about an axis (preferably horizontal) and incorporated into a single element, thus realizing a compact and safe structure such as will allow also of minimizing down times: the purpose of such a solution is therefore to optimize the machining operations by achieving a drastic reduction in the time taken to complete auxiliary tasks involving the workpiece, or rather to the extent that certain non machining operations (cleaning the work table, changing the work, removing waste) can be performed in what are effectively "hidden" times. A further advantage afforded by the unit disclosed is that it allows a complete isolation of the infeed-outfeed station from the machining enclosure inside which chips and dust are generated, thereby enhancing the activity of the operator.